What the Canadians want to do is their business. We cannot allow foreign governments to manipulate our presidential selection system by deciding to treat our candidates as their citizen, too. If they chose to designate Sarah Palin as the Duchess of Ontario, would that prevent us from electing her as our president? Of course not. The Canadian government can choose to do anything it wants.
We choose our presidents, because we're Americans. And, that's special!! ;-)